NEW DELHI: Delhi ranked as the most polluted among 33 states and Union territories with an annual mean PM2.5 concentration of 101 micrograms per cubic metre, 2.5 times the Indian standard and 20 times the WHO guideline, according to a new satellite-based analysis.
The report by the independent research organisation Centre for Research on Energy and Clean Air said Chandigarh recorded the second-highest annual average PM2.5 level at 70 micrograms per cubic metre during the study period from March 2024 to February 2025, followed by Haryana at 63 and Tripura at 62.
Assam (60), Bihar (59), West Bengal (57), Punjab (56), Meghalaya (53) and Nagaland (52) also exceeded the national standard.
Overall, 447 of the 749 districts (60 per cent) analysed breached the National Ambient Air Quality Standard (NAAQS) for annual PM2.5 of 40 micrograms per cubic metre.
The most polluted districts are heavily concentrated in a few states, the analysis showed.
Delhi (11 districts) and Assam (11 districts) together accounted for nearly half of the top 50, followed by Bihar (7) and Haryana (7). Other contributors include Uttar Pradesh (4), Tripura (3), Rajasthan (2) and West Bengal (2).
In several states, all monitored districts exceeded the NAAQS. These include Delhi, Assam, Punjab, Haryana, Chandigarh, Himachal Pradesh, Meghalaya, Tripura and Jammu and Kashmir.
Several others showed a large majority of districts breaching the standard, such as Bihar (37 of 38), West Bengal (22 of 23), Gujarat (32 of 33), Nagaland (11 of 12), Rajasthan (30 of 33) and Jharkhand (21 of 24).
Ladakh, Andaman and Nicobar Islands, and Lakshadweep were excluded from the analysis due to insufficient ground monitoring data during the study period.